CN116243573A

CN116243573A - Developer cartridge

Info

Publication number: CN116243573A
Application number: CN202211708988.8A
Authority: CN
Inventors: 王裕雯; 大冈一成; 岸勋朗; 桥本淳一
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 2018-03-30
Filing date: 2018-09-28
Publication date: 2023-06-09
Also published as: WO2019187237A1; US20200081371A1; CN111902776A; US10859942B2; US20220146960A1; CA3092208C; CN111902776B; US11249418B2; EP3805865B1; US20230280673A1; CA3092208A1; US10520853B2; JP2019179127A; EP3571550B1; US11693331B2; ES2845302T3; EP3805865A1; EP3571550A1; EP3571550A4; PL3571550T3

Abstract

A developer roller (12) is closer to a first end (113) of a casing (11) in a first direction than to a second end (114) of the casing (11) in the first direction. The first protrusion (13) extends in the second direction and is movable with the housing. When the first projection is supported by the support surface (41) of the first side plate (33) of the drum unit (3), the first projection bears the weight of the developer cartridge (1) and is away from the developing roller in the first direction and the third direction. The first pressure receiving surface (15) is farther from the developing roller than the first projection is from the developing roller in the third direction. The first pressure receiving surface receives a pressing force in a third direction from a pressing member (47) of a first side plate of the drum unit. The first projection is a first distance (D1) from the developing roller in a first direction. The first pressure receiving surface is a first distance or a second distance (D2) smaller than the first distance from the developing roller in the first direction.

Description

Developer cartridge

This application is a divisional application of the following patent applications:

application number: 201880003652.7

Filing date: 2018, 9, 28 days

The invention name is as follows: developer cartridge

Technical Field

The present disclosure relates to a developer cartridge.

Background

Electrophotographic image forming apparatuses known in the art include laser printers and Light Emitting Diode (LED) printers. For example, patent document 1 discloses an image forming apparatus including a developer cartridge and a drum unit. The drum unit includes a plurality of photosensitive drums. The developer cartridge is attachable to and removable from the drum unit. When the developer cartridge is attached to the drum unit, the developing roller of the developer cartridge contacts the corresponding photosensitive drum of the drum unit.

Each developer cartridge includes a developing roller shaft rotatable with the developing roller. When the developer cartridge is attached to the drum unit, the developer cartridge rotates around the developing roller shaft with respect to the drum unit due to the weight of the developer cartridge. The developer cartridge is then positioned relative to the drum unit.

[ citation list ]

[ patent literature ]

Japanese patent application laid-open No.2007-101635

Disclosure of Invention

[ technical problem ]

When the developer cartridge is attached to the drum unit, the developer cartridge pivots about the developing roller shaft with respect to the drum unit. The developing roller of the developer cartridge may apply a significantly varying contact pressure to the photosensitive drum of the drum unit according to the remaining amount of toner in the developer cartridge. This significantly varying contact pressure between the developer roller and the photoreceptor drum may cause the toner to be inappropriately transferred (white spots or color non-uniformities) to the paper outputting the image.

In accordance with the above-described problems, one or more aspects of the present invention relate to a structure that prevents a contact pressure between a photosensitive drum of a drum unit and a developing roller of a developer cartridge from significantly varying according to an amount of toner remaining in the developer cartridge.

[ problem solution ]

(1) A first aspect of the present invention provides a developer cartridge having the following structure. The developer cartridge includes a housing, a developing roller, a first projection, and a first pressure receiving surface. The housing extends in a first direction and may contain toner. The housing has a first end in a first direction and a second end remote from the first end in the first direction. The developing roller is rotatable about a roller axis extending in a second direction different from the first direction. The developing roller is closer to the first end than to the second end in the first direction. The developing roller has an exposed surface at a first end of the developing roller in the third direction and exposed outside the casing, and a covered surface at a second end of the developing roller in the third direction inside the casing. The first protrusion extends in the second direction and is movable with the housing. The first protrusion is located at a first outer surface of the housing at a first end of the housing in the second direction. The first projection may bear the weight of the developer cartridge when the first projection is supported by the support surface of the first side plate of the drum unit. The first projection is away from the developing roller in the first direction and the third direction. The first pressure receiving surface is farther from the developing roller than the first projection is from the developing roller in the third direction. The first pressure receiving surface may receive the pressing force in the third direction from the pressing member of the first side plate of the drum unit. The first projection is a first distance from the developing roller in a first direction. The first pressure receiving surface is spaced from the developing roller in the first direction by a first distance or a second distance, the second distance being smaller than the first distance.

With this structure, it is possible to suppress the contact pressure between the photosensitive drum of the drum unit and the developing roller of the developer cartridge from significantly varying according to the amount of toner remaining in the developer cartridge.

(2) Preferably, in the developer cartridge according to the first aspect, the first direction is different from the third direction.

(3) Preferably, the developer cartridge according to the first aspect or feature (2) is attachable to the drum unit in the first direction.

(4) Preferably, in the developer cartridge according to the first aspect or any one of the features (2) - (3), the first pressure receiving surface is configured to receive a pressing force directed from the cover surface toward the exposed surface in the third direction from the pressing member of the first side plate of the drum unit.

(5) Preferably, when the developer cartridge according to the feature (4) is attached to the drum unit, the first projection is supported by the support surface of the first side plate of the drum unit, and the first projection bears the weight of the developer cartridge.

With this structure, the first pressure receiving surface can receive the pressing force directed from the cover surface to the exposed surface while the first projection bears the weight of the developer cartridge. Therefore, the developing roller can be brought closer to the photosensitive drum without being affected by the weight of the developer cartridge.

(6) Further, when the developer cartridge according to the feature (5) is attached to the drum unit, it is preferable that the first pressure receiving surface receives a pressing force directed from the cover surface to the exposed surface in the third direction from the pressing member of the first side plate of the drum unit.

With this structure, when the developer cartridge is attached to the drum unit, the developing roller can be brought into contact with the photosensitive drum when a pressing force directed from the cover surface to the exposed surface is received at the first pressure receiving surface while the first projection is received by the supporting surface of the drum unit.

(7) Further, when the developer cartridge according to the feature (5) is attached to the drum unit, it is preferable that the first pressure receiving surface is pressed against the pressing member of the first side plate of the drum unit to receive a pressing force directed from the cover surface toward the exposed surface in the third direction.

With this structure, when the developer cartridge is attached to the drum unit, the first pressure receiving surface contacts the pressing member of the drum unit to be pressed toward the developing roller. The developing roller is thus brought into contact with the photosensitive drum of the drum unit.

(8) Preferably, the developer cartridge according to the first aspect or any one of the features (2) - (7) further comprises a first ring rotatable about the first projection, the first ring being cylindrical or polygonal.

With this structure, the first projection can slide with a small friction force with respect to the supporting surface of the drum unit, thereby bringing the developing roller close to the photosensitive drum of the drum unit.

(9) Preferably, in the developer cartridge according to the first aspect and any one of the features (2) - (8), the first projection is a member separate from the casing.

With this structure, the first projection can be assembled to the housing. Thus, flexibility in assembling the developer cartridge can be achieved.

(10) Preferably, in the developer cartridge according to the first aspect or any one of the features (2) - (9), the developing roller is located at a first end of the casing in the third direction, and the first pressure receiving surface is located at a second end of the casing in the third direction, the second end being distant from the first end.

(11) More preferably, the developer cartridge according to the first aspect or any one of the features (2) - (10) further comprises a second projection extending in the second direction and movable together with the casing. The second protrusion is located on the first outer surface. The second projection is farther from the developing roller than the first projection is from the developing roller in the first direction and the third direction. The second protrusion is configured to receive a pressing force directed from the second end of the housing in the first direction toward the first end of the housing in the first direction.

(12) Further preferably, the developer cartridge according to the feature (11) is configured to pivot about the first projection in response to the second projection receiving a pressing force directed from the second end of the housing in the first direction toward the first end of the housing in the first direction.

With this structure, the second projection can bear the pressing force directed from the second end of the housing toward the first end while the first projection bears the weight of the developer cartridge. Therefore, the developer cartridge can be pivoted so that the developing roller can be brought closer to the photosensitive drum without being affected by the weight of the developer cartridge.

(13) Preferably, in the developer cartridge according to the feature (11), the second projection is configured to receive a pressing force from the lock lever of the drum unit.

(14) In the developer cartridge according to the feature (11), it is further preferable that: when the developer cartridge is attached to the drum unit, the second projection receives a pressing force directed from the second end of the casing in the first direction toward the first end of the casing in the first direction from the locking lever of the drum unit; and the first projection is supported by the support surface of the first side plate of the drum unit, and the first projection bears the weight of the developer cartridge.

(15) Preferably, the developer cartridge according to the feature (14) pivots about the first projection in response to the second projection receiving a pressing force directed in the first direction from the second end toward the first end.

With this structure, when the developer cartridge is attached to the drum unit, the second projection receives a pressing force directed from the second end toward the first end, thereby pivoting the developer cartridge about the first projection to move the developer roller toward the photosensitive drum.

(16) Preferably, the developer cartridge according to the feature (15) further includes a projection extending in the second direction, the projection being located at a first end of the developing roller in the second direction. The projection contacts the first guide surface of the drum unit in response to the developer cartridge pivoting about the first projection.

With this structure, when the developer cartridge is attached to the drum unit, the projection contacts the first guide surface to restrict further pivoting of the developer cartridge. Positioning of the developing roller with respect to the photosensitive drum can be provided.

(17) In the developer cartridge according to the feature (16), it is preferable that: the developing roller includes a developing roller shaft extending in a second direction; and the projection is located at a first end of the developing roller shaft in the second direction.

With this structure, the first end of the developing roller shaft can serve as a projection.

(18) Further preferably, the developer cartridge according to any one of the features (11) - (17) further includes a second ring rotatable about the second projection, the second ring being cylindrical or polygonal.

With this structure, the developer cartridge can be smoothly pivoted to be attached to the drum unit with less friction.

(19) Further preferably, the developer cartridge according to any one of the features (11) - (18) further includes a third projection extending in the second direction and movable together with the casing. The third protrusion is located on a second outer surface of the housing, the second outer surface being remote from the first outer surface in a second direction. The third projection is configured to bear the weight of the developer cartridge when the third projection is supported by the second support surface of the second side plate of the drum unit. The third projection is away from the developing roller in the first direction and the third direction.

With this structure, the first projection and the third projection positioned opposite to each other in the second direction can be supported by the support surface and the second support surface of the drum unit, respectively. The developer cartridge can be stably supported.

(20) Further preferably, the developer cartridge according to the feature (19) further includes a second pressure receiving surface that is farther from the developing roller than the third projection is from the developing roller in the third direction. The second pressure receiving surface is remote from the first pressure receiving surface in a second direction. The second pressure receiving surface is configured to receive a pressing force in the third direction from the pressing member of the second side plate of the drum unit. The third projection is a first distance from the developing roller in the first direction, and the second pressure receiving surface is a first distance or a second distance from the developing roller in the first direction.

With this structure, when the developer cartridge is attached to the drum unit, the developer cartridge can be pressed at the first pressure receiving surface and the second pressure receiving surface, which are positioned opposite to each other in the second direction. The developer cartridge may be stably moved toward the photosensitive drum to allow the developer cartridge to be attached to the drum unit.

(21) Further preferably, in the developer cartridge according to the first aspect or any one of the features (2) - (20), the first projection is closer to the developing roller than to the second end of the casing in the first direction.

(22) Further preferably, in the developer cartridge according to the first aspect or any one of the features (2) - (20), the first pressure receiving surface extends beyond at least a portion of the first outer surface of the casing in the third direction.

(23) A second aspect of the present invention provides a developer cartridge having the following structure. The developer cartridge includes a housing, a developing roller, a first projection, and a second projection. The housing extends in a first direction and may contain toner. The housing has a first end in a first direction and a second end remote from the first end in the first direction. The developing roller is rotatable about a roller axis extending in a second direction different from the first direction. The developing roller is closer to the first end than to the second end in the first direction. The developing roller has an exposed surface and a covered surface. The exposed surface is located at a first end of the developing roller in the third direction and exposed outside the casing. The cover surface is located at a second end of the developing roller in the third direction within the housing. The first protrusion extends in the second direction and is movable with the housing. The first protrusion is located on a second outer surface of the housing, the second outer surface being located at a first end of the housing in a second direction. The first projection is away from the developing roller in the first direction and the third direction. The second projection extends in a second direction and is movable with the housing. The second protrusion is located on the first outer surface. The second projection is farther from the developing roller than the first projection is from the developing roller in the first direction and the third direction.

(24) Preferably, the developer cartridge according to the second aspect further includes a first ring rotatable about the first projection.

With this structure, the first projection can smoothly slide with less friction with respect to the drum unit.

(25) Preferably, the developer cartridge according to the feature (24) further includes a second ring rotatable about the second projection.

With this structure, the second projection can also smoothly slide with less friction with respect to the drum unit.

(26) Preferably, in the developer cartridge according to the second aspect or any one of the features (24) - (25), the first projection is closer to the developing roller than to the second end of the casing in the first direction.

(27) Preferably, the developer cartridge according to any one of the second aspects or features (24) - (26) further comprises a pressure receiving surface extending beyond at least a portion of the first outer surface of the housing in the third direction.

(28) Preferably, the developer cartridge according to any one of the second aspects or features (24) - (27) further comprises a coupler extending from the first outer surface of the housing in the second direction. The coupling is rotatable about a coupling axis extending in the second direction, and the coupling axis is located between the developing roller and the first projection in the first direction.

(29) Optionally, the developer cartridge according to any of the second aspects or features (24) - (27) further comprises a coupler extending from the first outer surface of the housing in the second direction. The coupler is rotatable about a coupling axis extending in a second direction. The first projection is located between the coupling axis and the second projection in the first direction and in the third direction.

(30) More preferably, in the developer cartridge according to any one of the second aspects or features (24) - (29), the first direction is different from the third direction.

(31) Preferably, the developer cartridge according to any one of the second aspects or features (24) - (30) is attachable to the drum unit in the first direction.

(32) More preferably, in the developer cartridge according to any one of the second aspects or features (24) - (31), the first projection is configured to bear a weight of the developer cartridge.

(33) More preferably, in the developer cartridge according to the feature (32), the first projection is configured to bear the weight of the developer cartridge when the first projection is supported by the support surface of the first side plate of the drum unit.

With this structure, the developer cartridge can pivot while the first projection bears the weight of the developer cartridge.

(34) More preferably, in the developer cartridge according to the second aspect or any one of the features (24) - (33), the second projection is configured to receive a pressing force directed from the second end of the casing in the first direction toward the first end of the casing in the first direction.

(35) More preferably, the developer cartridge according to the feature (34) is configured to pivot about the first projection in response to the second projection receiving a pressing force directed from the second end of the housing in the first direction toward the first end of the housing in the first direction.

With this structure, the developer cartridge is pivotable about the first projection toward the photosensitive drum of the drum unit by the second projection receiving a pressing force directed from the second end of the casing toward the first end while the first projection bears the weight of the developer cartridge.

(36) Further alternatively, in the developer cartridge according to the feature (34) or the feature (35), the second projection is configured to receive a pressing force directed from the second end of the casing in the first direction toward the first end of the casing in the first direction from the locking lever of the drum unit.

[ advantageous effects of the invention ]

With the structures according to the first and second aspects of the present disclosure, the contact pressure between the photosensitive drum of the drum unit and the developing roller of the developer cartridge can be restricted from significantly changing according to the amount of toner remaining in the developer cartridge.

Drawings

Fig. 1 is a conceptual diagram of an image forming apparatus;

fig. 2 is a perspective view of the drum unit and the developer cartridge;

fig. 3 is a perspective view of the developer cartridge;

Fig. 4 is a perspective view of the developer cartridge as viewed from a direction different from that of fig. 3;

fig. 5 is a side view of the developer cartridge at one end of the developer cartridge in the second direction;

fig. 6 is a side view of the developer cartridge at the other end of the developer cartridge in the second direction;

FIG. 7 is a perspective view of the drum unit;

fig. 8 is a side view of the drum unit illustrating an internal structure of the drum unit in a process in which one developer cartridge is attached to the drum unit;

fig. 9 is a side view of the drum unit illustrating an internal structure of the drum unit to which the developer cartridge is attached;

fig. 10 is a side view of the developer cartridge in the process of being attached to the drum unit;

fig. 11 is a side view of the developer cartridge to be attached to the drum unit; and

fig. 12 is a schematic diagram depicting the forces of interaction during attachment of the developer cartridge to the drum unit.

Detailed Description

Embodiments of the present disclosure will now be described with reference to the accompanying drawings.

The first direction herein refers to the longitudinal direction of each end face of the developer cartridge. The second direction here refers to a direction along the rotation axis of the photosensitive drum. The third direction here refers to a direction in which the plurality of photosensitive drums are aligned with each other. The first direction, the second direction and the third direction intersect each other (preferably at right angles).

1. Structure of image forming apparatus

Fig. 1 is a conceptual diagram of an image forming apparatus 100 according to an embodiment. The image forming apparatus 100 is an electrophotographic printer. The image forming apparatus 100 may be a laser printer or a Light Emitting Diode (LED) printer. As shown in fig. 1, the image forming apparatus 100 includes a drum unit 3 and a plurality of developer cartridges 1. The drum unit 3 includes a frame configured to hold the developer cartridge 1.

Fig. 2 is a perspective view of the drum unit 3 and the developer cartridge 1. The developer cartridge 1 may be separately attached to the drum unit 3. The drum unit 3 holding the developer cartridge 1 is configured to be attached to a body casing 101 of the image forming apparatus 100 (see fig. 1). Each developer cartridge 1 contains a different color toner (developer) (e.g., cyan, magenta, yellow, or black). The image forming apparatus 100 is configured to form (output) an image on a recording surface of a print sheet with toner supplied from the developer cartridge 1. The drum unit 3 in the present embodiment is configured to hold four developer cartridges 1. In some embodiments, the drum unit 3 may hold one to three, or five or more developer cartridges 1.

2. Structure of developer cartridge

Fig. 3 and 4 are perspective views of the developer cartridge 1. Fig. 5 and 6 show an end face of the developer cartridge 1 as viewed in the second direction. As shown in fig. 3 to 6, each of the developer cartridges 1 according to the present embodiment includes a casing 11, a developing roller 12, a stirrer (not shown), and a coupling 24.

The casing 11 is a housing configured to contain toner. The housing 11 has a chamber (not shown) configured to contain toner. The housing 11 extends in the second direction. The housing 11 has a first outer surface 111 and a second outer surface 112 remote from the first outer surface 111 in the second direction. The first outer surface 111 is one end surface (first end surface) of the housing 11 in the second direction. The longitudinal direction of the first outer surface 111 corresponds to the first direction. The second outer surface 112 is the other end surface (second end surface) of the housing 11 in the second direction. The longitudinal direction of the second outer surface 112 corresponds to the first direction. The housing 11 has a first end 113 in a first direction and a second end 114 remote from the first end 113 in the first direction. The housing 11 has a first end 11F in the third direction and a second end 11R distant from the first end 11F in the third direction.

The developing roller 12 is rotatable about a roller axis extending in the second direction. The developing roller 12 is located between the first outer surface 111 and the second outer surface 112 of the casing 11 in the second direction. The developing roller 12 is closer to the first end 113 than to the second end 114 in the first direction. The developing roller 12 is located at one end (first end 11F) of the casing 11 in the third direction. In other words, the developing roller 12 is located at one outer surface (third outer surface) of the casing 11 in the third direction.

More specifically, the developing roller 12 includes a cylindrical developing roller body and a cylindrical developing roller shaft 12c. The developing roller shaft 12c extends through the center of the developing roller body in the second direction. The developing roller body rotates together with the developing roller shaft 12c. The developing roller shaft 12c has both ends in the second direction rotatably supported by the respective end faces of the casing 11 in the second direction. More specifically, the developing roller shaft 12c has a first end 12cL in the second direction, which is rotatably supported by the first outer surface 111 of the casing 11, and a second end 12cR in the second direction, which is rotatably supported by the second outer surface 112 of the casing 11.

The developing roller 12 (developing roller body) has an exposed surface 12a and a covered surface 12b. The exposed surface 12a is located at one end (first end 12F) of the developing roller 12 in the third direction, and is exposed to the outside of the casing 11. The cover surface 12b is located at the other end (second end 12R) of the developing roller 12 in the third direction, and is located inside the casing 11. When the developer cartridge 1 is attached to the drum unit 3, the outer peripheral surfaces of the developing rollers 12 contact the outer peripheral surfaces of the respective photosensitive drums 31.

The agitator (not shown) may be rotatable about an agitator axis extending in the second direction. The agitator includes a plurality of agitating blades. The agitator is located between the first outer surface 111 of the housing 11 and the second outer surface 112 of the housing 11 in the second direction. In the first direction, the agitator is closer to the second end 114 than to the developer roller 12. The agitator rotates to agitate the toner contained in the chamber of the housing 11.

The coupling 24 shown in fig. 3 and 5 is configured to receive a driving force from the body casing 101 of the image forming apparatus 100. The coupler 24 is rotatable about a coupler axis extending in the second direction. The coupling 24 is closer to the second end 114 than to the developer roller 12 in the first direction. The coupler 24 has a recess 115 recessed inward in the second direction. When the developer cartridge 1 attached to the drum unit 3 is attached to the body casing 101 of the image forming apparatus 100, the drive shaft of the body casing 101 of the image forming apparatus 100 is received in the recess 115. The coupling 24 is thus connected to the drive shaft so as not to rotate relative thereto. Rotation of the drive shaft rotates the coupler 24. Rotation of the coupler 24 then rotates the developer roller 12 and agitator.

3. Structure of drum unit

The structure of the drum unit 3 will now be described mainly with reference to fig. 7. Fig. 7 is a perspective view of the drum unit 3.

As shown in fig. 7 to 9, the drum unit 3 includes a plurality of photosensitive drums 31, a first side plate 33, a second side plate 34, and a pullout plate 35. In the present embodiment, the drum unit 3 includes four photosensitive drums 31.

The photosensitive drum 31 is configured to transfer toner fed from the developer cartridge 1 to a print sheet. The photosensitive drums 31 are arranged in a row at a distance in the third direction. Each photosensitive drum 31 is cylindrical. Each photosensitive drum 31 has an outer peripheral surface. Each photosensitive drum 31 extends in the second direction. The outer peripheral surface of the photosensitive drum 31 is coated with a photosensitive material. Each photosensitive drum 31 is rotatable about a drum axis extending in the second direction.

The first side plate 33, the second side plate 34 and the pull-out plate 35 together define a frame. The frame is configured to hold the photosensitive drum 31. The frame has an opening at one end of the frame in a first direction (in this embodiment, the direction opposite to gravity).

The first side plate 33 supports a first end of the photosensitive drum 31 in the second direction. The first side plate 33 extends perpendicularly to the second direction. The first side plate 33 extends in the third direction. The first side plate 33 is a plate. The first side plate 33 includes a plurality of (four in the present embodiment) developer cartridge holders 30. The developer cartridge holder 30 is located on the inner surface of the first side plate 33 in the second direction. The developer cartridge holders 30 are arranged in rows at a distance in the third direction. The developer cartridge holder 30 of the first side plate 33 is configured to receive the first ends 1L (ends at the first outer surface 111) of the developer cartridges 1 in the first direction, respectively.

The second side plate 34 supports the second end of the photosensitive drum 31 in the second direction. The second side plate 34 extends perpendicular to the second direction. The second side plate 34 extends in the third direction. The second side plate 34 is a plate. The second side plate 34 includes a plurality of (four in the present embodiment) developer cartridge holders (not shown). The developer cartridge holder is located on an inner surface of the second side plate 34 in the second direction. The number of developer cartridge holders of the second side plate 34 is equal to the number of developer cartridge holders 30 of the first side plate 33. The developer cartridge holders of the second side plate 34 are configured to receive the second ends 1R (ends at the second outer surface 112) of the developer cartridges 1 in the second direction, respectively.

The pull-out plate 35 connects the second end 33F of the first side plate 33 in the third direction and the second end 34F of the second side plate 34 in the third direction. The pullout plate 35 extends perpendicularly to the third direction. The pullout plate 35 extends in the second direction. The pull-out plate 35 is a plate. The pull-out plate 35 has a handle 36. The handle 36 is located on the outer side surface of the pull-out plate 35 in the third direction. The handle 36 is gripped by the user to pull or push the drum unit 3 out of or into the body casing 101.

When the developer cartridge 1 is attached to the drum unit 3, the first end (first outer surface 111) of the casing 11 in the second direction is held by the developer cartridge holder 30 of the first side plate 33 and the second end (second outer surface 112) of the casing 11 in the second direction is held by the developer cartridge holder in the second side plate 34. When the developer cartridge 1 is attached to the drum unit 3, the outer peripheral surface (exposed surface 12 a) of the developing roller 12 contacts the outer peripheral surface of the corresponding photosensitive drum 31.

The image forming apparatus 100 having the above structure is configured to form an image on a print sheet. As the respective couplings 24 and the photosensitive drum 31 rotate, toner is fed from the chamber of the casing 11 to the outer peripheral surface of the photosensitive drum 31 by the developing roller 12. The toner held on the outer peripheral surface of the developing roller 12 moves from the developing roller 12 to the corresponding photosensitive drum 31 in accordance with the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 31. The electrostatic latent image is thereby developed into a visible toner image on the outer peripheral surface of the photosensitive drum 31. The toner image on the photosensitive drum 31 is then transferred onto a print sheet.

4. Detailed structure of attachment and removal

The structure according to the present embodiment for attaching and removing the developer cartridge 1 to and from the drum unit 3 will now be described with reference to fig. 3 to 12. Fig. 8 is a side view of the drum unit 3 showing the internal structure of the drum unit 3 in the process of attaching one developer cartridge 1. Fig. 9 is a side view of the drum unit 3 illustrating the internal structure of the drum unit 3 in which the developer cartridge 1 is attached. Fig. 11 is a side view of the developer cartridge 1 in the process of attaching to the developer cartridge holder 30 of the drum unit 3. Fig. 11 is a side view of the developer cartridge 1 attached to the developer cartridge holder 30 of the drum unit 3. Fig. 12 is a schematic diagram describing forces of interaction in the process of attaching the developer cartridge 1 to the developer cartridge holder 30 of the drum unit 3.

The developer cartridge 1 according to the present embodiment includes a first projection 13, a first ring 14, a first pressure receiving surface (pressure receiving surface) 15, a second projection 16, a second ring 17, a first projection 18, a third projection 19, a second pressure receiving surface 21, a fourth projection 22, and a second projection 23.

The first protrusion 13 extends in the second direction. The first projection 13 in the present embodiment is a separate member from the housing 11, and is fixed to the housing 11. In some embodiments, the first protrusion 13 may be integral with the housing 11. The first protrusion 13 is movable together with the housing 11. The first protrusion 13 is located on the first outer surface 111. More specifically, the first protrusion 13 protrudes outward from the first outer surface 111 in the second direction. As described in detail later, the first projection 13 can bear the weight of the developer cartridge 1. The first projection 13 is away from the developing roller 12 in the first direction and the third direction. As described in detail later, when the developer cartridge 1 is attached to the drum unit 3, the first projection 13 is supported by a support surface 41 (described later) of the drum unit 3.

The first ring 14 is cylindrical. The first ring 14 is rotatable around the first protrusion 13. The first ring 14 has a hollow. The first ring 14 receives the first protrusion 13 in the hollow. In some embodiments, the first ring 14 may not be cylindrical. For example, the first ring 14 may be polygonal. The developer cartridge 1 may not include the first ring 14. In this case, the outer peripheral surface of the first protrusion 13 may serve as a first ring.

The first pressure receiving surface 15 is an arc-shaped surface curved along an arc line centered on a straight line extending in the second direction. The first pressure receiving surface 15 is located inside the first outer surface 111 in the second direction. In the third direction, the first pressure receiving surface 15 is farther from the developing roller 12 than the first projection 13 is from the developing roller 12. The first pressure receiving surface 15 is located at a second end 11R (opposite to the developing roller 12) of the casing 11 in the third direction. In other words, the first pressure receiving surface 15 is located on the outer surface of the second end 11R of the housing 11 in the third direction. The first pressure receiving surface 15 extends beyond at least a portion of the first outer surface 111 of the housing 11 in the third direction.

The first projection 13 is located at a first distance D1 from the developing roller 12 in the first direction. The first pressure receiving surface 15 is located at a first distance D1 or a second distance D2 (d2+.d1) smaller than the first distance D1 from the developing roller 12 in the first direction. In the present embodiment, as shown in fig. 5 and 6, the distance between the first pressure receiving surface 15 and the developing roller 12 in the first direction is substantially equal to the first distance D1.

In the present embodiment, the first distance D1 may be defined as the maximum distance between the outer peripheral surface of the first projection 13 and the outer peripheral surface of the developing roller 12 in the first direction, and the second distance D2 may be defined as the maximum distance between the outer surface of the first pressure receiving surface 15 and the outer peripheral surface of the developing roller 12 in the first direction. In some embodiments, these distances may be defined differently. For example, the first distance D1 may be defined as a distance in the first direction between the center of the first projection 13 and the rotation center (axis) of the developing roller 12, and the second distance D2 may be defined as a distance in the first direction between the center of the circular arc defined by the outer surface of the first pressure receiving surface 15 and the rotation center (axis) of the developing roller 12. In other embodiments, the first distance D1 may be a distance in the first direction between the outer surface of the first projection 13 and the outer peripheral surface of the developing roller shaft 12c, and the second distance D2 may be a distance in the first direction between the outer surface of the first pressure receiving surface 15 and the outer peripheral surface of the developing roller shaft 12 c.

The second protrusion 16 extends in the second direction. The second projection 16 in the present embodiment is a separate component from the housing 11, and is fixed to the housing 11. In some embodiments, the second protrusion 16 may be integral with the housing 11. The second protrusion 16 is movable together with the housing 11. The second protrusion 16 is located on the first outer surface 111. More specifically, the second protrusion 16 protrudes outward from the first outer surface 111 in the second direction. The second projection 16 is farther from the developing roller 12 than the first projection 13 is from the developing roller 12 in the first and third directions. In other words, the second projection 16 is opposed to the developing roller 12 with respect to the first projection 13 in the first direction. The second projection 16 is opposite to the developing roller 12 with respect to the first projection 13 in the third direction. As described in detail later, when the developer cartridge 1 is attached to the drum unit 3, the second projection 16 is configured to receive a pressing force directed from the second end 114 to the first end 113 in the first direction.

The second ring 17 is cylindrical. The second ring 17 is rotatable around the second protrusion 16. The second ring 17 has a hollow. The second ring 17 receives the second protrusion 16 in the hollow. In some embodiments, the second ring 17 may not be cylindrical. For example, the second ring 17 may have a polygonal shape. The developer cartridge 1 may not include the second ring 17. In this case, the outer peripheral surface of the second protrusion 16 may serve as a second ring.

The first protrusion 18 extends in the second direction. The first projection 18 is located at a first end of the developing roller 12 in the second direction. More specifically, the first projection 18 is located at the first end 12cL of the developing roller shaft 12c in the second direction. The first projection 18 is a separate member from the developing roller 12, and is attached to the developing roller 12. More specifically, the first projection 18 is a separate member from the developing roller shaft 12c, and is attached to the developing roller shaft 12c. In some embodiments, the first projection 18 may be integral with the developer roller 12. More specifically, the first projection 18 may be integral with the developing roller shaft 12c. As described in detail later, when the developer cartridge 1 is attached to the drum unit 3, the first projection 18 contacts the guide 49 of the drum unit 3. The first projection 18 is thus used to position the developer cartridge 1 relative to the drum unit 3.

The third protrusion 19 shown in fig. 4 and 6 extends in the second direction. The third projection 19 in the present embodiment is a separate component from the housing 11 and is fixed to the housing 11. In some embodiments, the third protrusion 19 may be integral with the housing 11. The third protrusion 19 is movable together with the housing 11. The third protrusion 19 is located at the second outer surface 112. More specifically, the third protrusion 19 protrudes outward from the second outer surface 112 in the second direction. The third protrusion 19 is located on the axis of the first protrusion 13 extending in the second direction. As described in detail later, the third projection 19 and the first projection 13 together are configured to bear the weight of the developer cartridge 1. The developer cartridge 1 further includes a third ring (reference numeral not shown) rotatable about a third projection 19, which is similar to the first ring 14.

The second pressure receiving surface 21 is an arc-shaped surface curved along an arc line centered on a straight line extending in the first direction. The second pressure receiving surface 21 is distant from the first pressure receiving surface 15 in the second direction. The second pressure receiving surface 21 is located inside with respect to the second outer surface 112 in the second direction. The second pressure receiving surface 21 overlaps the first pressure receiving surface 15 when viewed in the second direction. In other words, the second pressure receiving surface 21 is farther from the developing roller 12 than the third projection 19 is from the developing roller 12 in the third direction.

The third projection 19 is located at a first distance D1 from the developing roller 12 in the first direction. The second pressure receiving surface 21 is located at a first distance D1 or a second distance D2 (d2+.d1) smaller than the first distance D1 from the developing roller 12 in the first direction.

The fourth protrusion 22 extends in the second direction. The fourth projection 22 in the present embodiment is a separate component from the housing 11, and is fixed to the housing 11. In some embodiments, the fourth protrusion 22 may be integral with the housing 11. The fourth protrusion 22 is movable together with the housing 11. The fourth protrusion 22 is located on the second outer surface 112. More specifically, the fourth protrusion 22 protrudes outward from the second outer surface 112 in the second direction. The fourth protrusion 22 is located on the axis of the second protrusion 16 extending in the second direction. The developer cartridge 1 has a fourth ring (reference numeral not shown) rotatable about a fourth projection 22, which is similar to the second ring 17.

The second protrusion 23 extends in the second direction. The second projection 23 is located at a second end of the developing roller 12 in the second direction. More specifically, the second projection 23 is located at the second end 12cR of the developing roller shaft 12c in the second direction. The second projection 23 is a separate member from the developing roller 12, and is attached to the developing roller 12. More specifically, the second projection 23 is a separate member from the developing roller shaft 12c, and is attached to the developing roller shaft 12c. In some embodiments, the second projection 23 may be integral with the developer roller 12. More specifically, the second projection 23 may be integral with the developing roller shaft 12c. The second protrusion 23 is located on the axis of the first protrusion 18 extending in the second direction. As described in detail later, the second projection 23 and the first projection 18 together serve to position the developer cartridge 1 with respect to the drum unit 3.

The image forming apparatus 100 according to the present embodiment includes the developer cartridge holder 30 of the first side plate 33 and the developer cartridge holder of the second side plate 34. More specifically, as shown in fig. 8 and 9, each of the developer cartridge holder 30 of the first side plate 33 and the developer cartridge holder of the second side plate 34 in the present embodiment includes a support 46, a pressing member 47, a lock lever 48, and a guide 49. The support 46, pressing member 47, locking lever 48, and guide 49 in each of the developer cartridge holders 30 of the first side plate 33 are paired with these components in the corresponding developer cartridge holders of the second side plate 34. Since each of the developer cartridge holders of the second side plate 34 has a symmetrical structure to each of the developer cartridge holders 30 of the first side plate 33, the developer cartridge holders 30 of the first side plate 33 will be mainly described below without repeatedly describing the developer cartridge holders of the second side plate 34.

As shown in fig. 10, the support 46 has a support surface 41. The support 46 protrudes inward from the inner surface of the first side plate 33 in the second direction. The support surface 41 faces in a direction opposite to the force of gravity. The support surface 41 is a flat surface perpendicular to the first direction. The support surface 41 supports the first projection 13 through the first ring 14 when the developer cartridge 1 is attached to the developer cartridge holder 30 of the drum unit 3.

The pressing member 47 has a first pressing surface 42. The pressing member 47 is located on the inner surface of the first side plate 33. The first pressing surface 42 is a flat surface substantially perpendicular to the third direction. The first pressing surface 42 can slide in the third direction with respect to the first side plate 33. The pressing member 47 includes a spring (not shown) as an elastic member. When the first pressing surface 42 moves toward the second end 3R of the drum unit 3 in the third direction (in a direction away from the pullout plate 35), the spring of the pressing member 47 presses the first pressing surface 42 rearward toward the first end 3F of the drum unit 3 in the third direction (toward the pullout plate 35). When the developer cartridge 1 is attached to the developer cartridge holder 30 of the drum unit 3, the first pressing surface 42 contacts the first pressure receiving surface 15 of the housing 11 of the corresponding developer cartridge 1. The first pressure receiving surface 15 receives a pressing force directed from the second end 3R of the drum unit 3 in the third direction toward the first end 3F of the drum unit 3 in the third direction from the first pressing surface 42.

The lock lever 48 is located at a first end 33U (an end in a direction opposite to gravity) of the first side plate 33 in the first direction. The locking lever 48 has a second pressing surface 43 and a guide surface 51. The guide surface 51 is an arc-shaped surface protruding inward in the second direction (see fig. 7). The second pressing surface 43 is a flat surface continuous with the guide surface 51. The locking lever 48 is pivotable about a pivot axis extending in the third direction between a locking position and a release position. When the lock lever 48 is at the lock position, the guide surface 51 is at least partially located between the first side plate 33 and the second side plate 34, and the second pressing surface 43 is substantially perpendicular to the first direction and faces the second end 3D of the drum unit 3 in the first direction. The guide surface 51 is farther from the second side plate 34 in the second direction when the locking lever 48 is in the release position than when the locking lever 48 is in the locking position. The lock lever 48 includes a spring (not shown) as an elastic member. The spring in the locking lever 48 presses the second pressing surface 43 toward the locking position. The second pressing surface 43 contacts the second projection 16 through the second ring 17 when the corresponding developer cartridge 1 is attached to the developer cartridge holder 30 of the drum unit 3. The second projection 16 receives a pressing force directed from the first end 3U of the drum unit 3 in the first direction toward the second end 3D (downward) from the second pressing surface 43.

The guide 49 has a first guide surface 44 and a second guide surface 45. The guide 49 is located on the inner surface of the first side plate 33. The guide 49 is arc-shaped in side view. The first guide surface 44 is a planar surface that is generally perpendicular to the first direction. The first guide surface 44 contacts the first projection 18 when the developer cartridge 1 pivots about the first projection 13 to move the developing roller 12 toward the photosensitive drum 31 during attachment of the developer cartridge 1 to the developer cartridge holder 30 of the drum unit 3. The first guide surface 44 is thus used to position the developer cartridge 1 relative to the drum unit 3.

The second guide surface 45 has a flat surface and an inclined surface continuous with the flat surface. The planar surface is generally perpendicular to the first direction. One end of the inclined surface in the third direction (one end closer to the first guide surface 44) is connected to the flat surface. The inclined surface is an inclined surface extending from the flat surface toward the second end 33D of the first side plate 33 in the first direction and toward the second end 33F of the first side plate 33 in the third direction. The second guide surface 45 is spaced apart from the first projection 18 in the first direction when the developer cartridge 1 pivots about the first projection 13 to move the developing roller 12 toward the photosensitive drum 31 during attachment of the developer cartridge 1 to the developer cartridge holder 30 of the drum unit 3.

6. Forces that interact when attaching a developer cartridge

Forces that interact during attachment of the developer cartridge 1 to the drum unit 3 will now be described with reference to fig. 8 to 12.

To attach the developer cartridge 1 to the drum unit 3, the user first holds the developer cartridge 1 with the first end 113 of the housing 11 in the first direction facing the second end 3D of the drum unit 3 in the first direction. The user then inserts the developer cartridge 1 into the corresponding developer cartridge holder (the developer cartridge holder 30 of the first side plate 33 and the developer cartridge holder of the second side plate 34) in the first direction toward the second end 3D of the drum unit 3 (see fig. 8). As a result, the first projection 13 is supported by the support surface 41 of the drum unit 3 through the first ring 14 in the first direction. Likewise, the third projection 19 is supported by the support surface 41 of the drum unit 3 through the third ring in the first direction. The supporting surface 41 bears the weight of the developer cartridge 1.

At the same time, as the user inserts the developer cartridge 1 into the drum unit 3 toward the second end 3D of the drum unit 3 in the first direction, the arc-shaped guide surface 51 is pushed by the second projection 16 (second ring 17) to smoothly pivot outward in the second direction against the pressing force of the spring of the lock lever 48. The lock lever 48 of the developer cartridge holder 30 is thereby moved to the release position. Also, in the developer cartridge holder of the second side plate 34, the guide surface 51 is pushed by the fourth projection 22 (fourth ring) to smoothly pivot outward against the pressing force of the spring of the lock lever 48, moving the lock lever 48 to the release position. The developer cartridge 1 is thereby allowed to move toward the second end 3D of the drum unit 3 in the first direction. The second projection 16 is closer to the second end 3D of the drum unit 3 in the first direction than the locking lever 48 is to the second end 3D of the drum unit 3 in the first direction. The fourth projection 22 is closer to the second end 3D of the drum unit 3 in the first direction than the corresponding locking lever 48 is to the second end 3D of the drum unit 3 in the first direction. Subsequently, the second pressing surface 43 under the pressing force of the spring of the corresponding locking lever 48 is pivoted inward in the second direction, and the locking lever 48 is placed in the locking position.

As shown in fig. 10, the second protrusion 16 (second ring 17) contacts the second pressing surface 43 in the locked position to receive a pressing force from the second pressing surface 43 directed from the second end 114 of the housing 11 toward the first end 113 of the housing 11 in the first direction. Similarly, the fourth protrusion 22 (fourth ring) contacts the second pressing surface 43 at the lock position to receive a pressing force from the second pressing surface 43 directed from the second end 114 of the housing 11 toward the first end 113 of the housing 11 in the first direction. At this position, the first projection 13 and the third projection 19 are each supported from below (from the second end 3D side of the drum unit 3) by the corresponding support surface 41 in the first direction. As a result, a torque around the first projection 13 (around the third projection 19) is generated in the developer cartridge 1. The developer cartridge 1 is thus caused to slightly pivot in the drum unit 3 about the first projection 13 (about the third projection 19) to move the developing roller 12 toward the photosensitive drum 31. As the developing roller 12 moves toward the photosensitive drum 31, the first projection 18 contacts the first guide surface 44 to stop the pivotal movement of the developer cartridge 1 about the first projection 13. At the same time, the second projection 23 contacts the first guide surface 44 to stop the pivotal movement of the developer cartridge 1 about the third projection 19. This contact determines the contact angle between the developing roller 12 and the photosensitive drum 31, and properly positions the developing roller 12 with respect to the photosensitive drum 31. In other words, the developer cartridge 1 is positioned in the drum unit 3.

Further, as the user inserts the developer cartridge 1 into the drum unit 3 toward the second end 3D of the drum unit 3 in the first direction, each first pressing surface 42 is pushed by the first pressure receiving surface 15 or the second pressure receiving surface 21, and moves toward the second end 3R of the drum unit 3 in the third direction against the pressing force of the spring in the pressing member 47. Thus, the first pressure receiving surfaces 15 receive the pressing forces directed from the cover surfaces 12b to the exposed surfaces 12a in the third direction from the corresponding first pressing surfaces 42 while or after the developer cartridge 1 is slightly pivoted about the first projection 13. Also, thereby, the first pressure receiving surfaces 15 receive the pressing forces directed in the third direction from the cover surfaces 12b toward the exposed surfaces 12a from the corresponding first pressing surfaces 42 while or after the developer cartridge 1 is slightly pivoted about the third projection 19. At this position, the support surface 41 receives the weight of the developer cartridge 1 applied through the first projection 13 and the third projection 19. So that each of the first projection 13 (first ring 14) and the third projection 19 (third ring) slides toward the first end 3F of the drum unit 3 in the third direction while being supported by the corresponding support surface 41. This moves the developing roller 12 further toward the photosensitive drum 31, and allows the outer peripheral surface of the developing roller 12 (developing roller body) to contact the outer peripheral surface of the photosensitive drum 31 with an appropriate contact pressure. At this position, since the supporting surface 41 bears the weight of the developer cartridge 1, the weight of the developer cartridge 1 is less likely to affect the contact pressure between the developing roller 12 and the photosensitive drum 31. This structure can suppress the contact pressure between the developing roller 12 and the photosensitive drum 31 from significantly changing according to the amount of toner remaining in the developer cartridge 1.

Just before the outer peripheral surface of the developing roller 12 (developing roller body) contacts the outer peripheral surface of the photosensitive drum 31, the first projection 18 is held between the first guide surface 44 and the second guide surface 45 in the first direction (see fig. 10). The developing roller 12 can be positioned appropriately with respect to the photosensitive drum 31. The inclined surface of the second guide surface 45 smoothly guides the developing roller 12 toward a position between the flat surfaces of the first guide surface 44 and the second guide surface 45.

In the above manner, when the developer cartridge 1 is attached to the drum unit 3, the developer cartridge 1 is properly positioned with respect to the drum unit 3. At this time, since the lock lever 48 is in the lock position, the developer cartridge 1 is not easily separated from the drum unit 3 even if the image forming apparatus 100 is applied with vibration or impact. The structure according to the present embodiment allows the developer cartridge 1 to be reliably attached to or removed from the drum unit 3.

[ list of reference symbols ]

1: developer cartridge

11: outer casing

12: developing roller

12a: exposed surface

12b: covering a surface

12c: developing roller shaft

13: first protrusion

14: first ring

15: first pressure receiving surface

16: second protrusion

17: second ring

18: first protrusion

19: third protrusion

22: fourth protrusion

23: second protrusions

31: photosensitive drum

41: support surface

42: a first pressing surface

43: a second pressing surface

44: a first guide surface

45: a second guide surface

48: locking lever

100: image forming apparatus with a plurality of image forming units

111: a first outer surface

112: second outer surface

113: first end

114: second end

D1: first distance

D2: second distance

Claims

1. A developer cartridge, characterized by comprising:

a housing extending in a first direction and configured to contain toner, the housing having a first end in the first direction and a second end remote from the first end in the first direction;

a developing roller rotatable about a roller axis extending in a second direction different from the first direction, the developing roller being closer to the first end than to the second end in the first direction, the developing roller having an exposed surface at a first end of the developing roller in a third direction and exposed at an outside of the casing, and a cover surface at a second end of the developing roller in the third direction and inside of the casing;

a first projection extending in the second direction and movable with the casing, the first projection being located at a first outer surface of the casing in the second direction, the first projection being configured to bear a weight of the developer cartridge when the first projection is supported by a support surface of a first side plate of a drum unit, the first projection being away from the developing roller in the first direction and the third direction; and

A first pressure receiving surface farther from the developing roller than the first projection in the third direction, the first pressure receiving surface being configured to receive a pressing force in the third direction from a pressing member of the first side plate of the drum unit;

wherein the first projection is a first distance from the developing roller in the first direction; and is also provided with

Wherein the first pressure receiving surface is at the first distance from the developing roller or at a second distance smaller than the first distance in the first direction.

2. The developer cartridge according to claim 1, wherein the first direction is different from the third direction.

3. A developer cartridge according to claim 1 or 2, wherein said developer cartridge is attachable to said drum unit in said first direction.

4. A developer cartridge according to any one of claims 1 to 3, wherein said first pressure receiving surface is configured to receive, from said pressing member of said first side plate of said drum unit, said pressing force directed from said covering surface toward said exposed surface in said third direction.

5. The developer cartridge according to claim 4, wherein when the developer cartridge is attached to the drum unit, the first projection is supported by the support surface of the first side plate of the drum unit, and the first projection bears the weight of the developer cartridge.

6. The developer cartridge according to claim 5, wherein the first pressure receiving surface receives the pressing force directed from the cover surface toward the exposed surface in the third direction from the pressing member of the first side plate of the drum unit when the developer cartridge is attached to the drum unit.

7. The developer cartridge according to claim 5, wherein when the developer cartridge is attached to the drum unit, the first pressure receiving surface is pressed against the pressing member of the first side plate of the drum unit to receive the pressing force directed from the cover surface toward the exposed surface in the third direction.

8. The developer cartridge according to any one of claims 1 to 7, further comprising a first ring rotatable about the first projection, the first ring being cylindrical or polygonal.

9. The developer cartridge according to any one of claims 1 to 8, wherein the first projection is a separate member from the casing.

10. The developer cartridge according to any one of claims 1 to 9, wherein the developing roller is located at a first end of the casing in the third direction, and the first pressure receiving surface is located at a second end of the casing in the third direction, the second end being remote from the first end of the casing.

11. The developer cartridge according to any one of claims 1 to 10, further comprising:

a second projection extending in the second direction and movable together with the housing, the second projection being located on the first outer surface, the second projection being farther from the developing roller than the first projection is from the developing roller in the first direction and the third direction, the second projection being configured to receive a pressing force directed from the second end of the housing in the first direction toward the first end of the housing in the first direction.

12. The developer cartridge according to claim 11, wherein the developer cartridge is configured to pivot about the first projection in response to the second projection receiving the pressing force directed from the second end of the housing in the first direction toward the first end of the housing in the first direction.

13. The developer cartridge according to claim 11, wherein the second projection is configured to receive the pressing force from a lock lever of the drum unit.

14. A developer cartridge according to claim 11, wherein said second projection receives, from a lock lever of said drum unit, said pressing force directed from said second end of said housing in said first direction toward said first end of said housing in said first direction when said developer cartridge is attached to said drum unit, said first projection being supported by said support surface of said first side plate of said drum unit, and said first projection bearing the weight of said developer cartridge.

15. The developer cartridge according to claim 14, wherein the developer cartridge pivots about the first projection in response to the second projection receiving the pressing force directed from the second end toward the first end in the first direction.

16. The developer cartridge according to claim 15, further comprising a projection extending in the second direction, the projection being located at a first end of the developing roller in the second direction;

Wherein the projection contacts the first guide surface of the drum unit in response to the developer cartridge pivoting about the first projection.

17. The developer cartridge according to claim 16, wherein the developing roller includes a developing roller shaft extending in the second direction, and the projection is located at a first end of the developing roller shaft in the second direction.

18. The developer cartridge according to any one of claims 11 to 17, further comprising a second ring rotatable about the second projection, the second ring being cylindrical or polygonal.

19. The developer cartridge according to any one of claims 11 to 18, further comprising:

a third projection extending in the second direction and movable together with the casing, the third projection being located at a second outer surface of the casing, the second outer surface being distant from the first outer surface in the second direction, the third projection being configured to bear a weight of the developer cartridge when the third projection is supported by a second support surface of a second side plate of the drum unit, the third projection being distant from the developing roller in the first direction and the third direction.

20. The developer cartridge according to claim 19, further comprising:

a second pressure receiving surface farther from the developing roller than the third projection in the third direction, the second pressure receiving surface being distant from the first pressure receiving surface in the second direction, the second pressure receiving surface being configured to receive a pressing force in the third direction from a pressing member of the second side plate of the drum unit;

wherein the third projection is spaced from the developing roller by the first distance in the first direction, and the second pressure receiving surface is spaced from the developing roller by the first distance or the second distance in the first direction.

21. The developer cartridge according to any one of claims 1 to 20, wherein the first projection is closer to the developing roller than to the second end of the casing in the first direction.

22. The developer cartridge according to any one of claims 1 to 20, wherein the first pressure receiving surface extends beyond at least a portion of the first outer surface of the housing in the third direction.

23. A developer cartridge, characterized by comprising:

a first projection extending in the second direction and movable with the casing, the first projection being located on a first outer surface of the casing in the second direction, the first projection being remote from the developing roller in the first direction and the third direction; and

a second projection extending in the second direction and movable with the housing, the second projection being located at the first outer surface, the second projection being farther from the developing roller than the first projection is from the developing roller in the first direction and the third direction.

24. The developer cartridge according to claim 23, further comprising a first ring rotatable about the first projection.

25. The developer cartridge according to claim 24, further comprising a second ring rotatable about the second projection.

26. The developer cartridge according to any one of claims 23 to 25, wherein the first projection is closer to the developing roller than to the second end of the casing in the first direction.

27. The developer cartridge according to any one of claims 23 to 26, further comprising a pressure receiving surface extending beyond at least a portion of the first outer surface of the housing in the third direction.

28. The developer cartridge according to any one of claims 23 to 27, further comprising:

a coupling extending from the first outer surface of the casing in the second direction, the coupling being rotatable about a coupling axis extending in the second direction, and the coupling axis being located between the developing roller and the first projection in the first direction.

29. The developer cartridge according to any one of claims 23 to 27, further comprising a coupling extending from the first outer surface of the casing in the second direction, the coupling being rotatable about a coupling axis extending in the second direction;

wherein the first projection is located between the coupler axis and the second projection in the first direction and the third direction.

30. The developer cartridge according to any one of claims 23 to 29, wherein the first direction is different from the third direction.

31. A developer cartridge according to claims 23 to 30, wherein said developer cartridge is attachable to a drum unit in said first direction.

32. The developer cartridge according to any one of claims 23 to 31, wherein the first projection is configured to bear a weight of the developer cartridge.

33. The developer cartridge according to claim 32, wherein the first projection is configured to bear a weight of the developer cartridge when the first projection is supported by a support surface of the first side plate of the drum unit.

34. The developer cartridge according to any one of claims 23 to 33, wherein the second projection is configured to receive a pressing force directed from the second end of the casing in the first direction toward the first end of the casing in the first direction.

35. The developer cartridge according to claim 34, wherein the developer cartridge is configured to pivot about the first projection in response to the second projection receiving the pressing force directed from the second end of the housing in the first direction toward the first end of the housing in the first direction.

36. A developer cartridge according to claim 34 or 35, wherein said second projection is configured to receive, from a lock lever of a drum unit, said pressing force directed from said second end of said casing in said first direction toward said first end of said casing in said first direction.